Fracture resistance of endocrowns made from different CAD/CAM materials after prolonged fatigue aging

Abstract

<p><strong>Objectives: </strong>The aim of this study was to evaluate the fracture resistance of endocrowns made of experimental short fiber-reinforced CAD/CAM block (SFRC CAD) in comparison with different commercial CAD/CAM materials.</p><p><strong>Materials and methods: </strong>In this study, 60 sound mandibular molar teeth with similar occlusal sizes (± 1 mm) were used. Standard preparations simulating an endocrown cavity were prepared and the teeth were divided into four groups randomly. After the digital photoimpression of the prepared cavities using a dental intraoral scanner (CEREC), the restorations were designed (4 mm high) and milled using IPS e.max, Cerasmart 270, Katana Avencia and SFRC CAD blocks (n = 15/per group). Restorations were cemented with self-adhesive dual-cure resin cement (G-Cem One). The specimens were immersed in a 37 °C water bath within the chewing simulator. Following cyclic fatigue aging for 1.000.000 cycles (F_max=150 N), a quasi-static load was applied using a universal testing machine at a speed of 1 mm/min. Fractography analysis was conducted using optical microscopy.</p><p><strong>Results: </strong>According to the data obtained, there are statistically significant differences in fracture resistance values between different CAD/CAM materials (p < 0.05). The highest values were observed in the experimental SFRC CAD group (3025 N), while the lowest values were observed in the IPS e.max group (2295 N).</p><p><strong>Conclusions: </strong>The type of CAD/CAM restorative material influences the fracture resistance of endocrowns. SFRC CAD blocks could potentially serve as an alternative material for endocrown restorations in the future.</p><p><strong>Clinical relevance: </strong>Endocrowns fabricated from SFRC CAD blocks have demonstrated promising fracture behavior, suggesting their suitability for clinical testing.</p>